As a case study, I thought I'd see how I would go about converting the PC I've most recently played: a 4th level Necromancer/Monk from the Iron Kingdoms, named Dalina Iaganevna. I'll mention some additions to the rules that I've made that may help the transition; you can find most of these on the forums here, and I plan to get them on the Runequest Wiki. I will also try to determine how she could be converted without the book.
Firstly, she's a 1st level Necromancer, and a 3rd level Monk. Instead of setting up a rule, I'd just give the player a budget of skill points to divide, with some recommendations. For Dalina, it seems reasonable to give her 10% in Wizardry and Read Magic, and 30% in Martial Arts. (If you're not using Wizardry and Read Magic as skills, you can assign appropriate runes and give her 10% in Runecasting.) All these are assuming we're adding the % to her default skill level.
D&D stats are STR 13 DEX 18 CON 8 INT 14 WIS 12 CHA 12. That could be easily translated as STR 13 CON 8 DEX 18 INT 14 POW 12 CHA 12. For SIZ, she's portrayed as a petite woman with a severe attitude, so let's make her SIZ 10.
This means she gets 3 CAs, has a Damage Modifier of +0, and gets 2-5 hp per hit location. Using an optional rule we've discussed in the Martial Arts thread, she can add 1/5 her Martial Arts skill to Str and Siz to determine her Damage Modifier with her unarmed attacks and specially trained monk weapons. This means that her effective STR + SIZ + 1/5 MA% = 29, so she does +1d2 with a martial arts attack. She has 12 magic points, and a strike rank modifier of 16.
Her skills in D&D were Escape Artist +9, Gather Information +5, Handle Animal +4, Intimidate +6, Jump +8, Listen +2, Perform (Warbard) +4, Sense Motive +3, Spellcraft +6, Spot +3, Swim +2, Tumble +12. The easiest way to deal with this would probably to just multiply these modifiers by 5% and apply them to equivalent Runequest skills.
Her feats were Iron Will, Improved Initiative, Weapon Finesse, Scribe Scrolls, Improved Grapple, and Deflect Arrows. Iron Will could be a +10% to her Persistence skill. Weapon Finesse could be a +25% to her weapon skill (Katrena's Hook). Scribe Scrolls is simply the Read Magic skill she gets as a Wizard. Improved Grapple would be a +20% bonus in her wrestling skill. Deflect Arrows can either be considered a special advantage or legendary ability, or it could just be modelled by +15% do her Dodge skill.
That leaves Improved Initiative. I have a thread about making Initiative a skill, which replaces some of the MRQ rules for determining initiative and combat actions. Otherwise, you could just consider it an advantage that raises her Strike Rank Modifier by +2, to 18.
She didn't have any magic items, so those do not need to be considered.
Her saving throws were +2 Fort, +7 Ref, and +8 Will. This could be translated as 10% Resistance, 35% Dodge, and 40% Persistence. This includes the +10% for the Iron Will feat.
Dalina is a necromancer, which means by the D&D rules she is barred from casting conjuration and illusion spells. There is no direct way to model this prohibition in Runequest unless the option of allowing disadvantages is employed. In Iron Kingdoms, this makes sense, since Necromancy is regarded as a special taint -- the GM may even decide that Necromancy is a different skill from Wizardry, and assign Dalina's scores to that skill.
I will assume that her ability to prepare spells is limited by her POW, so she can prepare up to 12 total magnitudes of spells. Spells that she has prepared, she can cast as many times as she has prepared, even without her spell book. But since this is not D&D, if she has her spell book she can cast any of her spells directly out of that without a penalty.
She does not have the Spell Mastery feat, so she has not "memorized" any spells. If she had, she'd be able to prepare of cast those spells, even without her spell book.
I've noted a special Iron Kingdoms limitation for Dalina, which would apply to anyone trying to cast necromancy magic: She has to make a Fort Save of DC 16 to avoid 2 points of nonlethal damage when she casts one of her Necromany spells. This can be modelled as a opposed Resilience roll against 80%; failure means that she is fatigued.
As a monk, she gets a +10' bonus to her basic move. Perhaps this can be modelled as a +10% bonus to her Athletics skill. Evasion and Still Mind can either be modelled as legendary abilities, or else as bonuses to her Dodge and Persistence skills.
I've noted a number of conditional bonuses for Dalina. Converting these as +5% per +1 of D&D bonus, these are +10% to Read Magic checks involving Necromancy magic, +10% to Intimidation and Handle Animal skill checks, +5% to spot checks, and +10% synergy bonus to Athletics and Acrobatics checks involving Jumping.
She can read and write Khadoran and Cygnarion as bonus languages. As a native of Khador, I'd rule a 140% fluency is speaking Khadoran and a 70% fluency in reading Khadoran. Her skill levels in Cygnarion would be considerably lower.
Her spell book includes all the cantrips (0-level spells) in the PHB, plus the following 1st level spells: Cause Fear, Shield, True Strike, Hold Portal, Protection from Evil, Comprehend Languages, Identify, Magic Missile, Expeditious Retreat, Magic Weapon, Mage Armor, and two spells she's created herself: Black Patch, and Blackflame Armor. These could be replaced with Runequest equivalents, or else converted into Runequest terms. Be sure to take into account that Runequest characters can take a lot less damage because it is all concentrated on one hit location.
I hope this helps.
